Pt alloy for ornament

ABSTRACT

A novel alloy contains Pt as a principal component and also contains 0.1 to 15% Ru and 0.1 to 15% Ir in weight rate in Pt to overcome a problem in that Vickers hardness (Hv) of the conventional Pt-based alloys do not correspond to requirements in diversified ornaments because of their respective Vickers hardness (Hv): Hv 125 to 135 for Pt—Pu-based alloys and Hv 80 to 100 for Pt—Ir-based alloys.

BACKGOURND OF THE INVENTION

1. Field of the Invention

The present invention relates to a Pt alloy for an ornament, which can be used as raw materials of plate materials, wire rods, and process and cast materials thereof, including rings, necklaces, brooches, earrings, pierced earrings, and tiepins.

2. Description of Related Art

Pt alloys for ornaments, which have been known in the art, include Pt—Ru alloys and Pt—Ir alloys (see, for example, JP 2003-321719 A and JP 2003-96525 A).

Furthermore, Pt—Pd-based Pt alloys prepared by additive Ru and/or Ir to Pt—Pd alloys have been also known in the art (see, for example, JP 2-43333 A).

The conventional Pt-based alloys have their respective Vickers hardness (Hv): Hv 125 to 135 for Pt—Ru-based alloys, Hv 80 to 100 for Pt—Ir-based alloys, and Hv 120 to 135 for Pt—Pd-based alloys additive with Ru and/or Ir.

However, in many cases, those Vickers hardness do not correspond to requirements in diversified ornaments. Conventionally, in particular, Pt-based alloys have been mainly worn by old people. In recent years, the products of Pt-based alloys also have gained popularity among young people and also have been worn by them. Based on this fact, rings, pierced earrings, earrings, and the other ornaments tend to thinner and smaller and the ways of wearing them also become diversified, while causing problems in strength enough to cope with troubles such as scratches and deformation.

The present invention has been made to solve the foregoing problems. Therefore, an object of the present invention is to provide a Pt-based alloy for an ornament having hardness enough to endure scratches and deformation.

SUMMARY OF THE INVENTION

The present invention provides an alloy that contains Pt as a principal component and also contains 0.1 to 15% Ru and 0.1 to 15% Ir in weight rate in Pt.

Also, the present invention provides a Pt-based alloy that contains 0.1 to 14% Ru, 0.1 to 14% Ir, 0.1 to 5.0% Ag, and 0.1 to 5.0% Cu in weight rate in Pt.

Also, the present invention provides a Pt-based alloy that contains 0.1 to 14% Ru, 0.1 to 14% Ir, 0.1 to 5.0% Ga, and 0.1 to 5.0% In in weight rate in Pt.

Furthermore, the present invention provides a Pt-based alloy that contains 0.1 to 14% Ru, 0.1 to 14% Ir, 0.1 to 5.0% Ag, 0.1 to 5.0% Cu, 0.1 to 5.0% Ga, and 0.1 to 5.0% In in weight rate in Pt.

According to those alloy compositions, the basic composition of the Pt—Ru—Ir-based alloy showed a Vivkers hardness (Hv) of 150 or more in the as-cast condition. In addition, the composition of Pt—Ru—Ir—Ag—Cu-based alloy showed a Vickers hardness (Hv) of 170 or more. Furthermore, the composition of the Pt—Ru—Ir—Ag—Cu—Ga—In-based alloy showed a Vickers hardness (Hv) of 160 or more in the as-cast condition.

From those values, the composition of the Pt—Ru—Ir-based alloy showed excellent hardness, compared with alloy having 85% Pt, 90% Pt, and 95% Pt in weight ratio. Furthermore, the reason of additive other elements such as Ag, Cu, Ga, and In to the above composition of the Pt—Ru—Ir-based alloy is as follows: Ornament raw materials are not only provided for wire rods or plate materials but also applied in casting production. Thus, they may demand casting properties. For fulfilling such demands, for example, fluidity and casting surface were improved by the addition of Ag and Cu and also a decrease in melting point was attained by the addition of Ga and In.

The addition of 0.1 to 5.0% Ru to the composition of the alloy is for exerting an effect on hardness. Less than 0.1% Ru causes no effect, while more than 5.0% Ru increases the number of blow holes generated in the alloy.

The addition of 0.1 to 5.0% Ir to the composition of the alloy is for exerting an effect on hardness. When the content of Ir is less than 0.1%, it does not contribute to miniaturization of alloy crystals. Thus, the hardness of the alloy is not influenced by the additive of Ir. In other words, no effect of Ir added can be obtained. When the content of Ir exceeds more than 5.0%, the alloy is difficult to be processed because of being hardened and fragile.

The addition of less than 0.1% of Ag to the composition of the alloy causes no improvement in fluidity and casting surface, while more than 5.0% of Ag causes a decrease in hardness.

When Cu is added to the composition of a Pt- or Pd-based alloy, Cu may be expected to cause age-hardening of the alloy. However, the addition of less than 0.1% of Cu does not cause any effect. For considering the balance with the contents of other metals added, the upper limit of Cu was set to 5.0%.

When each addition of Ga and In is less than 0.1%, no dropping effect is exerted on the melting point of the alloy. When the addition amount is more than 5.0%, the alloy becomes fragile and then becomes difficult to be processed, resulting in the alloy unsuitable to ornamental use.

Consequently, the present invention intends to increase the hardness of a Pt-based alloy for an ornament not by the independent additive of one of Ru and Ir but by the addition of Ru and Ir to the composition of the alloy to obtain a multi-element alloy. Besides, an improvement of hardness can be attained when the alloy is provided as a multi-element alloy added with Ag and Cu. In addition, the addition of Ga and In brings about an effect of providing an unprecedented new ornamental material in terms of its hardness and melting point.

EXAMPLES

TABLE 1 Casting Blow Melting Pt Ru Ir Ag Cu Ga In Hardness Castability surface hole point Example 1 85 5 10 185 good good null 1752 Example 2 90 3 7 168 excellent excellent null 1748 Example 3 95 2 3 155 excellent excellent null 1751 Example 4 85 3 7 3 2 174 good excellent null 1713 Example 5 90 2 5 2 1 163 excellent excellent null 1733 Example 6 95 1 2 1 1 151 excellent excellent null 1772 Example 7 85 3 7 3 2 186 excellent good null 1628 Example 8 90 2 5 2 1 177 excellent good null 1557 Example 9 95 1 2 1 1 173 excellent excellent null 1672 Example 10 85 1 5 3 2 3 1 166 good good null 1625 Example 11 90 1 2 2 1 3 1 147 good good null 1593 Example 12 95 1 2 0.5 0.5 0.5 0.5 143 good good null 1688 Component: Weight % Hardness: Hv Melting point: ° C.

TABLE 2 Casting Blow Melting Pt Pd Ru Ir Cu Co Hardness Castability surface hole point Pt850 85 10 5 125 excellent excellent slight 1730 Pt900 90 10 80 excellent excellent Null 1740 Pt950 95 5 120 excellent excellent Null 1775 Pt850 85 10 3 2 110 good good slight 1750 Pt900 90 7 3 115 excellent excellent Null 1765 Pt950 95 5 90 good good null 1780 Component: Weight % Hardness: Hv Melting point: ° C.

As listed in Table 1, a Pt-based alloy added with both Ru and Ir attained an increase in hardness. We have found that the hardness of such an alloy largely surpasses that of alloy independently added with one of Ru and Ir.

In addition, a Pt—Ru—Ir-based alloy added with both Ag and Cu kept its sufficient hardness while lowering its melting point without causing blow holes and rough casting surface, resulting in good casting properties.

In addition, a Pt—Ru—Ir-based alloy added with both Ga and In showed a significant drop of melting point. Furthermore, a Pt—Ru—Ir—Ag—Cu-based alloy added with both Ga and In showed a significant drop of melting point without causing blow holes, resulting in a good cast. Therefore, the Pt—Ru—Ir—Ag—Cu-based alloy can be sufficiently available as a Pt alloy for an ornament.

Those tests were carried out using a high-frequency induction furnace. The respective alloy samples were prepared. Then, each of them was subjected to a lost wax method to thereby obtain a high-temperature investment material. Subsequently, it was subjected to burning at 900° C. and then subjected to a high-frequency induction casting furnace, resulting in a test sample. Each test sample was subjected to abrasive finishing with JIS R 6253 waterproof abrasive paper (#1000), followed by observing the surface condition of the sample. As comparative samples, ornamental materials were prepared under the same conditions as those described above, except of using the conventional procedures to provide test samples. 

1. A Pt alloy for an ornament, comprising 0.1 to 15% Ru, 0.1 to 15% Ir, and the remainder consisting of Pt in weight rate.
 2. A Pt alloy for an ornament, comprising 0.1 to 14% Ru, 0.1 to 14% Ir, 0.1 to 5.0% Ag, 0.1 to 5.0% Cu, and the remainder consisting of Pt in weight rate.
 3. A Pt alloy for an ornament, comprising 0.1 to 14% Ru, 0.1 to 14% Ir, 0.1 to 5.0% Ga, 0.1 to 5.0% In, and the remainder consisting of Pt in weight rate.
 4. A Pt alloy for an ornament, comprising 0.1 to 14% Ru, 0.1 to 14% Ir, 0.1 to 5.0% Ag, 0.1 to 5.0% Cu, 0.1 to 5.0% Ga, 0.1 to 5.0% In, and the remainder consisting of Pt in weight rate. 